Will quitting sugar make you lose weight?

Short answer

Yes. But not because sugar is special: it is because you eat fewer calories. When sugar was swapped for the same calories of other carbs, body weight did not change.

Will quitting sugar make you lose weight?
'Sugar = the main cause of fat gain' — does this formula hold?
Many people say they lost weight after cutting out sweets. But whether that came from sugar itself or from eating fewer calories is a different question. We checked it step by step.
Cutting sugar does take weight off
Eating freely but with less sugar: 0.8 kg
An analysis that pooled studies where food intake was not controlled found that people who cut sugar lost 0.80 kg. The other way around, people who ate more sugar gained 0.75 kg. How much sugar you eat does move your weight.
Sugary drinks matter most
Take them out and weight drops; add them and it rises
An analysis of 16 randomized trials with 1,343 people found that adding sugary drinks raised weight by 0.83 kg, and removing them lowered it by 0.49 kg. In 6 trials with 1,729 people who swapped sugary drinks for water or zero-calorie drinks, adults weighed about 1 kg less for as long as the swap lasted.
What if calories stay the same?
Swapping sugar for other carbs: 0.04 kg
In the same analysis, trials that kept calories equal and only replaced sugar with other carbohydrates found a weight difference of 0.04 kg. That is practically no change. The researchers concluded that sugar changes body weight through calories.
Can you lose weight while eating sugar?
With fewer calories, people lost weight even at 43% sugar
42 people dieted for 6 weeks on about 1,100 kcal a day. One group got 43% of calories from sugar (about 118 g), the other only 4%. Both groups lost weight and body fat, and the high-sugar group did not lose less.
Fruit juice worked the same way
Once calories were counted, the weight gain disappeared
In an analysis of 100% fruit juice and body weight, studies that did not account for calories eaten found that people who drank more juice gained 0.21 kg more. In studies that adjusted for calories, there was no gain (-0.08 kg). Juice added weight by its calories.
Summary: quitting sugar works through calories
Sugar has no special magic
Cutting sugar took off 0.8 kg on average, and removing sugary drinks took off 0.49 kg. But when the same calories came from other foods, weight stayed the same. Cutting calorie-heavy items like sugary drinks first and watching your total intake is enough.